(1) Field of the Invention
The present invention relates to a mobile switch leveling, lining and tamping machine for vertically and laterally adjusting the position of a track switch comprised of a main track consisting of two rails fastened to ties, each rail having a field side and a gage side, and a track section laterally adjacent the main track, the machine comprising a machine frame, a leveling and lining tool carrier frame linked to the machine frame, power-actuated track lifting and lining drive means connecting the carrier frame to the machine frame for vertically and laterally adjusting the carrier frame, a pair of flanged wheels supporting the carrier frame on the main track for mobility therealong, each flanged wheel engaging a respective one of the rails and serving as a track lining tool, a respective power-operated, vertically and transversely adjustable track lifting tool mounted on the carrier frame for gripping each rail at one side thereof, and a leveling and lining reference system including a main track position sensing device, the leveling and lining reference system controlling actuation of the track lifting and lining drive means in response to the main track position sensed by the device.
(2) Description of the Prior Art
U.S. pat. No. 4,627,360, dated Dec. 9, 1986, discloses a machine of this type. The transversely adjustable tamping unit of this machine has tamping tools which may be independently pivoted in planes extending transversely to the track to enable even the most difficult areas of a track switch to be tamped by at least one of the tamping tools while any tamping tool encountering an obstacle is pivoted out of the way. To enable even very heavy switches with complicated rail configurations to be gripped for vertical and lateral movement, the track leveling and lining unit, which is supported on the track by two pairs of flanged rollers, has a strong rail-engaging lifting hook for each rail and these lifting hooks are transversely and vertically adjustable by hydraulic cylinder-piston drives. This enables the hooks to engage either the head or the base of each rail. Such switch leveling, lining and tamping machines are of great importance in track maintenance and rehabilitation work because the proper leveling and lining of track switches is very valuable due to the high cost of building such switches. However, despite the control of the leveling and lining operations by the reference system of the machine, the accuracy of the track lifting to obtain the desired level is impaired because of the weight of the adjacent track section branching off the main track in the switch and attached thereto by long ties, which causes an imbalance to the left or the right of the main track. Therefore, it is often necessary to re-work the branch track section and to adjust its level again under the control of the reference system before the ties of the adjacent track section are tamped.
U.S. pat. No. 4,323,013, dated Apr. 6, 1982, also discloses a mobile track leveling, lining and tamping machine which may be used in tangent tracks as well as in track switches. This machine comprises a track leveling and lining tool carrier frame which has a projecting center pole linked to the machine frame and is supported by a pair of flanged wheels on the track, which also serve as lining tools. Two lifting and two lining drives link the carrier frame to the machine frame to transmit the required leveling and lining forces to the track. A rail gripping device at each side of each flanged wheel comprises a pair of gripping rollers pivotal into and out of gripping engagement with the field and gage sides of the associated rail. Furthermore, a vertically and transversely adjustable rail gripping hook is arranged between the pairs of gripping rollers to enable even the heaviest switches to be lifted. In one embodiment, only a single pair of gripping rollers is associated with each gripping hook. In this arrangement, each rail is securely clamped between the flanged wheel engaging the gage side of the rail and at least one gripping roller and/or hook engaging the field side of the rail even in very difficult track configurations. However, while these machines have been used with great success, the unbalance produced by the branch track in the switch results in the hereinabove-outlined disadvantages and often subjects the lifting and/or lining drives to excessive stress. In an effort to alleviate this, it has been proposed to equip the machine with hoists providing an auxiliary support for the branch track section but this involves additional operating personnel and impedes the progress of the operation considerably. The hoists must be engaged and disengaged intermittently as the machine advances from tie to tie for tamping, which is very time-consuming and makes the operation uneconomical.
Still another mobile track leveling, lining and tamping machine has been disclosed in U.S. pat. No. 4,342,263, dated Aug. 3, 1982, which incorporates a two-part leveling and lining tool carrier frame with a lower carrier frame part whose central pole is linked to the machine frame and whose rear portion has a pair of flanged rollers supporting the carrier frame on the track. The upper carrier frame part is centrally linked to the lower part and carries a respective transversely displaceable and pivotal lifting hook associated with each flanged roller. The upper part is vertically adjustable on the lower part to make the lifting hooks vertically adjustable. The tool carrier frame is longitudinally adjustable relative to the machine frame. Since only a single rail gripping tool is provided for each rail, this machine cannot be used for lifting heavy track sections, such as switches, nor can it handle difficult rail configurations occurring in track switches. The previously described disadvantageous imbalance produced during lifting by the branch track is even more noticeable in this arrangement.
The track leveling and lining unit of the leveling, lining and tamping machine disclosed in British patent No. 2,140,061, published Nov. 21, 1984, similarly has a single pair of flanged wheels supporting the unit on the track rails and serving as lining tools, and a rail gripping hook or roller gripping the field side of each rail associated with each lining tool. This arrangement has the above-indicated disadvantages.
An apparatus for measuring the lateral distance between adjacent tracks has been disclosed in U.S. pat. No. 3,990,154, dated Nov. 9, 1976. This apparatus may be mounted on a track liner and enables the position of an adjacent track to be surveyed while the track liner advances. The apparatus comprises a roller head engaging one rail of the adjacent track and being telescopingly arranged for displacement transversely to the track to indicate position measurements of the adjacent track. It also comprises a measuring axle connected to the track liner engageable without play with a selected rail of the track and generating an electrical measuring signal. This apparatus enables the lateral distance of the adjacent track to be accurately measured and recorded, for example while the track liner is in operation.